InterviewSolution
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InterviewSolution
This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
When light rays enter the eye, most of the refraction occurs at the.A. crystalline lensB. outer surface of the corneaC. irisD. pupil |
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Answer» Correct Answer - B When light rays enter the eye, most of the refraction occurs at the outer surface of cornea. |
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| 2. |
The change in focal length of an eye lens is caused by the action of the.A. pupilB. retinaC. irisD. ciliary muscles |
| Answer» The action of ciliary muscles holding the eye lens change the focal length of eye lens enabling the eye to focus the image of objects at varying distances. Choose (iv) is correct. | |
| 3. |
Which of the folowing statement is correct ?A. A person with myopia can see distant objects clearlyB. A person with hypermetropia can see nearby objects clearlyC. A person with myopia can see nearby objects clearlyD. A person with hypermetropia cannot see distant objects clearly. |
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Answer» Correct Answer - C A person with myopia can see nearby objects clearly. |
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| 4. |
Which of the following statements is correct regarding the propagation of light of different colours of white light in air ?A. Red light moves fastestB. Blue light moves faster than green lightC. All the colours of the white light move with the same speed.D. Yellow light moves with the mean speed as that of the red and the violet light. |
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Answer» Correct Answer - C Different colours of white light in vacuum//air move with the same speed. |
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| 5. |
Why do different colours deviate through different angles on passing through a prism ? |
| Answer» This is because different colours travel through glass with different speeds, and glass has different refractive index for different colours. | |
| 6. |
Physics teacher was explaning to his students in class that our eyes can live even after our death. He told them that by donating our eyes after we die, one pair of our eyes can give vision to two corneal blind people. Eye donors may being to any sex or any age group. People suffering from diabetes, hypertension, asthma or any other non-communicable disease can donate eyes. Eye Banks have been established for this purpose, where you can pledge to donate your eye after your death. Read the above passage and answer the following questions : (i) Can people who have been using spectacles or those who have been operated for cataract donate their eyes ? (ii) Why is the pledge necessary ? (iii) Do you intend to make such a pledge ? Why ? |
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Answer» (i) Yes, people who have been using spectacles or those who have been operated for cataract can donate their eyes. (ii) The eyes have to be removed from your dead body and then implanted in two corneal blind people. Your permission in the from of pledge is essential. Infact, the pledge is to be signed in the presence of your near and dear ones. who will be incharge of the body after you die. (iii) Yes, I am determined to make a pledge for such a noble cause. I would have already used my eyes for the whole of my life. After I die, if both my eyes can be used to give vision to two corneal blind people, I will be blessed not only by those two people, but also by Gold almightly. Helping the under privileged creatures without losing anything is a wonderful thought and action. |
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| 7. |
Due to gradual weakening of ciliary muscles and diminishing flexibility of the eye lens, a certain defect of vision arises. Write the name of this defect. Name the type of lens required by such persons to improve the vision. Explain the structure and function of such a lens. |
| Answer» The name of this defect is Myopia or short sightedness. For details,. | |
| 8. |
Nooper needs a lens of power `- 4.5 D` for correction of her vision. (a) What kind of defect in vision is she suffering from ? (b) What is the focal length and nature of corrective lens ? ( c) Draw ray diagrams showing the defected eye and correction for the defect. (d) What are the causes of this defect ? |
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Answer» (a) As power of lens is negative, she must be suffering from myopia. (b) As `f = (100)/(P) :. F = (100)/(-4.5) = (-100 xx 2)/(9) = -22.2 cm`. ( c) The corrective lens must be concave. |
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| 9. |
A person with a myopic eye cannot see objects beyond `1.2 m` distinctly. What should be the type of corrective lens to restore proper vision ? |
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Answer» Here, distance of far point, `x = 1.2 m` For viewing distant objects, focal length of corrective lens, `f = -x = -1.2 m` Thus, `P = (1)/(f) = (1)/(-1.2) = -0.83 D` The lens must be concave. |
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| 10. |
For a normal eye, the least distance of distinct vision isA. 25 mB. 2.5 cmC. 25 cmD. 2.5 m |
| Answer» Correct Answer - 25 cm | |
| 11. |
(a) A student suffering from myopia is not able to see distinctly the objects placed beyond `5 m`. Two possible reasons due to which this defect of vision may have arisen. With the help of ray diagrams, explain : (i) Why the student is unable to see distinctly the objects placed beyond `5 m` from his eyes. (ii) The type of corrective lens used to restore proper vision and how this defect is corrected by the use of this lens. (b) If in this case, numerical value of focal length of corrective lens is `5 m`, find the power of the lens as per the new cartesion sign convention. |
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Answer» (a) N/A (b) A normal eye is unable to focus on an object placed within `10 cm` from the eye, because the near point of a normal human eye is `25 cm`. |
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| 12. |
What is meant by dispersion of white light ? Describe the formation of rainbow in the sky with the help of a diagram. (b) What is hypermetropia ? Draw ray diagrams to show the image formation of an object by (i) hypermetropic eye (ii) correction made with a suitable lens for hypermetric eye. |
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Answer» (a) Dispersion of white is the phenomenon of splitting of white light into its constituent seven colours on passing through a glass prism. For formation of rainbow in the sky, (b) Hypermetropia is that defect of human eye, by virtue of which, it can see clearly the objects lying at large distances from the eye. But the nearby objects cannot be seen clearly by the hypermetropic eye. For image formation, (b) and (c ), |
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| 13. |
The far point of a myopic eye is at `50 cm`. Calculate the power of the lens to correct his vision. |
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Answer» Here, distance of far point `x = 50 cm, power P = ?` As `f = - x, f = - 50 cm` Thus, power, `P = (100)/(f) = (100)/(-50) = - D` Negative sign indicates that the lens used is concave. |
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| 14. |
Explain the phenomenon of dispersion of white light through a glass prism, using suitable ray diagram. |
| Answer» Dispersion of light through a prism is the phenomenon of splitting of white light into its constituent colours on passing through the prism.The cause of dispersion is that different colours have different wavelengths.Therefore, they bend through different angles on passing through the prism. | |
| 15. |
The human eye forms the image of an object at itsA. corneaB. irisC. pupilD. retina |
| Answer» Correct Answer - retina | |
| 16. |
A narrow beam of white light is shown to pass through a triangular glass prism. After passing through the prism, it produces a specturm XY on a screen. (a) State the colour seen at `X and Y`. (b) Why do different colours of white light bend through different angles with respect to the incident beam of light ? . |
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Answer» (a) Colour seen at `X` is violet, and colour seen at `Y` is red. (b) Different colours bend through different angles because speed of different colour through glass is different and hence refraction index of glass for different colours is different. |
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| 17. |
A narrow beam of white light is shown to pass through a triangular glass prism. After passing through the prism, it produces a specturm XY on a screen. (a) State the colour seen at `X and Y`. (b) Why do different colours of white light bend through different angles with respect to the incident beam of light ? . |
| Answer» Splitting of white light into its constituent colours occurs because diferent colours have different wavelengtha. They deviate through different angles on passing through the prism. | |
| 18. |
The human eye can focus objects at different distances by adjusting the focal length of the eye lens. This is due toA. presbyopiaB. accommodationC. near-sightednessD. far-sightedness |
| Answer» accommodation | |
| 19. |
The human eye can focus objects at different distances by adjusting the focal length of the eye lens. This is due to.A. presbyopiaB. near sightednessC. accommodationD. far - sightedness |
| Answer» The property of the eye to adjust the focal length of eye lens is called accommodation. Choice (iii) is correct. | |
| 20. |
A person wears eye glasses with a power of `-5.5 D` for distance viewing. His doctor prescribes a correction of `+ 1.5 D` for his near vision. What is the focal length of his distance viewing part of the lens and also for near vision section of the lens ? |
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Answer» (i) For distance viewing, `f = ?, P = -5.5 D` Clearly, `f = (100)/(P) = (100)/(-5.5) = -18.2 cm` (ii) For near vision correction `P = + 1.5 D` Therefore, `f = (100)/(P) = (100)/(1.5) = 66.7 cm`. |
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| 21. |
A certain person can see clearly objects lying between `20 cm and 250 cm` from his eye. What spectacles are required to enable him to see distant objects clearly ? When he is wearing these spectacles, what is his least distance of distinct vision ? |
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Answer» Correct Answer - `P = -1 D` Distance of far point, `x = 100 cm` To see the moon clearly, he has to use specs with lens of focal length, `f = -x = -100 cm` `P = (100)/(f) = (100)/(-100) = -1 D`. |
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| 22. |
Why does clear sky appear blue ?A. blue light gets absorbed in the atmosphereB. ultraviolet radiations are absorbed in the atmosphereC. violet and blue lights get scattered more than light of all other colours by the atmosphereD. light of all other colours is scattered more than the violet and blue colour lights by the atmosphere. |
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Answer» Correct Answer - C The clear sky appears blue because violet and blue lights get scattered more than lights of all other colours by the atmosphere. This is primarily bacause the wavelengths of these colours are smaller than those of other colours. |
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| 23. |
Which of the following phenomena contributes significantly to the reddish appearance of the sun at sunrise or sunset ?A. Dispersion of lightB. Scattering of lightC. Total internal reflection of lightD. Reflection of light from the earth |
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Answer» Correct Answer - B Reddish appearance of sun at sunrise or sunset is due to least scattering of red light. |
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| 24. |
Why does clear sky appear blue ? |
| Answer» When sunlight passes through the atmosphere, it is scattered by molecules of air and other fine particles. As their size is smaller than the wavelength of light, therefore, blue colour (of shorter wavelength) is scattered more strongly than the red colour (of larger wavelength). The scattered blue light entres our eyes and the clear sky looks blue. | |
| 25. |
(a) Which phenomenon accounts for advanced sunrise and delayed sunset ? (b) Which phenomenon accounts for blue colour of clear sky ? |
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Answer» (a) Atmospheric refraction is responsible for advanced sunrise and deleyed sunset. (b) Blue coloue of clear sky is on account of scattering of sunlight. |
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| 26. |
Why are danger signals red in colour ?A. is scattered the most by smoke or fogB. is scattered the least by smoke or fogC. is absorbed the most by smoke or fogD. moves fastest in air. |
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Answer» Correct Answer - B The danger signals are red because among all other colours, red colour is scattered the least by smoke or fog. This is primarily because wavelength of red colour is the largest. |
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| 27. |
(a) Which lens is used for correcting a mypoic eye ? (b) Which lens is used for correcting a hypermetropic eye ? |
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Answer» (a) For correcting a myopic eye, we use a concave lens of suitable focal length. (b) For correcting a hypermetropic eye. We use a convex lens of suitable focal length. |
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| 28. |
The near point of a defective eye is `25 cm` from the eye. Calculate focal length of the lens required by her to read a book placed at `20 cm`. |
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Answer» Here, `u = -20 cm, v = -25 cm, f = ?` From `(1)/(f) = (1)/(v) - (1)/(u) = (1)/(-25) + (1)/(20) = (-4 + 5)/(100) = (1)/(100) , f = 100`. The lens must be convex, as focal length is positive. |
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| 29. |
What is the condition for minimum deviation through then prism ? What is prism formula ? |
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Answer» The condition for minimum deviation through a prism is that angle of incidence (i) is equal to angle of emergence ( e).In that case, the refracted ray `EF` becomes parallel to the base `bC` of the prism. If `D_m` is the angle of minimum deviation, then the prism formula is `mu =(sin(A + D_m)//2)/(sin A//2)` Here, `mu`is refraction index of the material of the prism. |
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| 30. |
What is the order of wavelength of visible light and audible sound? |
| Answer» The order of wavelength of visible lights is `10^-7 m`. | |